ABSTRACT Older sexual and gender minority (SGM) populations experience significant disparities in morbidity and disability compared with their heterosexual and cisgender counterparts. There are two primary explanations as to why physical health, mental health, and disability outcomes may differ for older SGM adults compared to older heterosexual and cisgender adults: 1) experiences of minority stress that negatively affect health over the life course, and 2) differences in the kind and quality of social networks and support in older age. In this study we develop and test a new conceptual model that integrates these two disparate areas of research by applying a multilevel approach to understanding how minority stress processes work. We contend that social networks mediate the relationship between minority stress and health. Social network effects may be negative, exacerbating the effects of negative life experiences of discrimination or violence by reinforcing feelings of negative marginality relative to dominant societal values and structures. Alternatively, social networks may buffer the effects of negative life experiences among SGM adults whose networks include more positive valuations of SGM identities. To test this model, we will collect in-depth ego-centric network data over three waves from 800 SGM adults aged 50 to 70 years and residing in the metropolitan statistical areas of three midsize cities in the US South: Nashville, TN; Birmingham, AL; and Raleigh, NC. Participants will be recruited using multiple face-to-face, community and targeted online methods in order to ensure inclusion of more isolated individuals or individuals who are less involved with community organizations. Surveys will be administered using a web-based instrument developed specifically for assessing multidimensional aspects of personal networks, physical and mental health, and experiences of minority stress.